Technical library

a) Macrophage differentiation in 384‑well plates
At PromoCell, macrophage differentiation is routinely performed in T75 flasks or 6‑well plates.
Differentiation in 384-well formats has not been tested internally.
Based on practical considerations, differentiation in very small well formats is likely to be challenging, mainly because:

• It is difficult to thoroughly wash the wells after the attachment phase.
• Incomplete removal of non‑adherent cells can negatively affect differentiation quality.
• Small volumes increase sensitivity to handling variability.

b) Detachment and re‑plating of mature macrophages

• Detachment of mature macrophages is possible
• However, re‑attachment is associated with significant cell loss, typically in the range of 30–50%
• This loss should be taken into account when planning downstream experiments.

After completion of differentiation (day 7/8 of the protocol), monocyte‑derived dendritic cells (DCs) should be maintained in:

• Complete Dendritic Cell Generation Medium or
• Dendritic Cell Generation Medium XF, including all cytokines.

Culture recommendations
Because dendritic cells are metabolically active, the medium should be changed every 3 days.
Under these conditions, we have observed that the dendritic cell phenotype remains stable for up to 7 days after differentiation is completed.

The Macrophage Detachment Solution (C‑41330) acts directly on the cell membrane to enable efficient detachment of macrophages.
Following detachment, the cells are in a particularly sensitive state. The addition of Human Serum Albumin (HSA) to the PBS wash buffer serves an important protective function:

• HSA supports regeneration and stabilization of the cell membrane
• It protects macrophages from detrimental effects during the critical phase immediately after detachment

This helps to maintain cell integrity and viability prior to downstream applications.

PromoCell HDMEC pre‑screened cells (C‑12215) are isolated from juvenile foreskin.

PromoCell Human Pulmonary Microvascular Endothelial Cells (HPMEC, C‑12281) are isolated from the lung parenchyma.
During the isolation process, all large vessels are removed beforehand. As a result, the majority of HPMEC originate from pulmonary capillaries.

PromoCell cell pellets (C‑14**) are supplied in RNAlater^TM Solution, which allows for two established approaches to RNA isolation.
 
Option 1: Remove RNAlater^TM prior to RNA extraction

• Centrifuge the sample at 5,000×g for 10 minutes at 4 °C.
• Carefully remove the supernatant (RNAlater^TM).
• Proceed with RNA extraction using your standard protocol.

Note: Due to the high density of RNAlater^TM, higher centrifugal forces are required to efficiently pellet the cells.
 
Option 2: Direct RNA isolation from RNAlater^TM
If no visible cell pellet forms after centrifugation, RNA can also be isolated directly from the RNAlater^TM solution:

• Add 2 ml of 10× lysis buffer directly to the sample.
• Proceed with RNA purification according to your standard RNA isolation protocol.

For chondrogenic differentiation of human mesenchymal stem cells (hMSC), it is essential that the cells do not adhere to the culture surface.
During differentiation, hMSCs aggregate and form spheroids that float freely in the medium. Therefore:

• No specific plate brand is required
• Any 96‑well U‑bottom plate that is suitable for suspension culture can be used
• The critical requirement is the U‑bottom geometry, which supports spheroid formation and prevents cell attachment

Yes, the differentiation capacity of human mesenchymal stem cells (hMSCs) does change over time and is influenced by the number of population doublings (PDs) the cells have undergone.
 
Observed differentiation capacity over time
PromoCell has tested the differentiation of hMSCs into adipocytes, chondrocytes, and osteoblasts.
Good differentiation rates are still observed after approximately 10 population doublings.
However, with increasing population doublings, the differentiation potential gradually declines.
 
Best practice for differentiation experiments
To achieve optimal differentiation efficiency, it is recommended to use early‑passage cells with a low number of population doublings.

In some cases, yes - but not for all differentiation lineages. The suitability of morphological assessment depends on the specific differentiation pathway.

Adipogenic differentiation

• Yes, adipogenic differentiation can be identified morphologically without staining. Differentiated cells show intracellular lipid vesicles, which are clearly visible by light microscopy.

Osteogenic differentiation

• No clear morphological changes are typically observed.
• To confirm osteoblastic differentiation, it is recommended to perform Alizarin Red S staining to detect matrix mineralization.

Chondrogenic differentiation

• Chondrogenic differentiation is usually performed as 3D spheroid cultures, not in 2D monolayers.
• Morphology alone is insufficient. Alcian Blue staining is indispensable to visualize proteoglycan production and confirm differentiation.

Neurogenic differentiation

• Neurogenic differentiation can be identified by the development of a characteristic neuronal morphology and
• visualized by staining Nissl bodies, RNA-rich rough endoplasmic reticulum structures that are characteristic of neurons.

 

Human mesenchymal stem cells (MSCs) derived from bone marrow, adipose tissue, and umbilical cord matrix originate from different tissues but show largely comparable biological properties and core functions.
All MSC types retain the ability to differentiate into mesenchymal lineages. However, depending on their tissue of origin, they may show a preference for differentiation toward certain cell types, while exhibiting lower efficiency toward others.
 
Tissue‑specific differentiation tendencies
MSC‑BM (bone marrow–derived MSCs)

• Very strong differentiation into osteoblasts (bone cells)
• Very good differentiation into chondrocytes and adipocytes

MSC‑UC (umbilical cord–derived MSCs)

• Very strong differentiation into chondrocytes
• Lower differentiation efficiency into adipocytes and osteoblasts

MSC‑AT (adipose tissue–derived MSCs)

• Very strong differentiation into adipocytes (fat cells)